ISSN 0439-755X
CN 11-1911/B

Acta Psychologica Sinica ›› 2022, Vol. 54 ›› Issue (8): 867-880.

• Reports of Empirical Studies •

### Neural correlates of consciousness of emotional faces and the unconscious automatic processing: Evidence from event-related potentials (ERPs)

SUN Bo, ZENG Xianqing, XU Kaiyu, XIE Yunting, FU Shimin

1. Department of Psychology and Center for Brain and Cognitive Sciences, School of Education, Guangzhou University, Guangzhou 510006, China
• Published:2022-08-25 Online:2022-06-23

Abstract:

The neural correlates of consciousness (NCCs) are debatable due to the confounding effects of subjective reports. In addition, although previous studies have suggested that vMMN is relatively insensitive to the manipulation of visual attention, the relationship between vMMN and visual consciousness remains unclear. The inattentional blindness paradigm can not only effectively manipulate visual consciousness, but also explore the conscious processing without relying on subjective reports. Therefore, we used this paradigm to manipulate visual consciousness. Moreover, we introduced emotional (happy and fearful) faces, which are biologically and socially significant visual stimuli, to explore NCCs and the relationship between automatic detection of changes and visual consciousness.
Fifty-six Chinese participants took part in the present study. We recorded electroencephalography (EEG) in three phases. In phase A, the participants needed to detect changes of the red dots. However, because they were not informed of the existence of emotional faces, 26 participants were unconscious of the task-irrelevant emotional faces. In phase B and C, all participants were informed about the emotional faces. Thus, they were conscious of the emotional faces. Specifically, in phase B, the participants still needed to detect changes of the red dots, and the emotional faces are task-irrelevant. However, in phase C, the participants were asked to detect changes of emotional faces, and thus emotional faces were task-relevant. To check the conscious state of emotional faces, participants were required to fill out an awareness questionnaire after completing phases A and B. Then the participants were divided into unconscious group and conscious group according to their conscious state of emotional faces in phase A.
For NCCs, two analyses of ERP amplitude of standard stimuli in Phase A and B of the unconscious group were performed. First, for the ERPs at PO7 and PO8 electrodes, a three-factor repeated-measures analysis of variance (rANOVA) of Phase (A, B) × Emotion (Fear, Happy) × Hemisphere (PO7, PO8) was used. Second, for the ERPs at the three electrodes of FCZ, CZ and CPZ, a three-factor rANOVA of Phase (A, B) × Emotion (Fearful, Happy) × Electrodes (FCZ, CZ and CPZ) was adopted. Similarly, two three-factor rANOVA were used for the effect of task relevance. However, exploring the effect of task relevance requires an analysis of the ERPs of standard stimuli in phase B and C of all participants. For vMMN, we analyzed the ERPs at PO7 and PO8 electrodes during the 250~350 ms window of time.
Results can be summarized as following. (1) For NCCs, the ERPs at PO7 and PO8 during the 200~300ms window of time were analyzed, which yielded a significant main effect of Phase [F(1, 25) = 16.385, p < 0.001, η2p = 0.396]. This showed that the emotional faces in phase B evoked stronger negativity than in phase A for the unconscious group, suggesting that the conscious processing of emotional faces evoked visual awareness negativity (VAN). The ERPs at PO7 and PO8 during the 400~600 ms window of time were analyzed, which yielded a significant main effect of Phase [F(1, 25) = 15.79, p = 0.001, η2p = 0.39]. This showed that the emotional faces in phase B evoked stronger positivity than in phase A for the unconscious group, suggesting that the conscious processing of emotional faces evoked late occipital positivity (LOP). Moreover, the ERPs at FCZ, CZ and CPZ during the 300~400ms window of time were analyzed, which yielded a significant main effect of Phase [F(1, 25) = 11.481, p = 0.002, η2p = 0.32]. This showed that the emotional faces in phase B evoked stronger positivity than in phase A for the unconscious group, suggesting that the conscious processing of emotional faces evoked late positivity (LP).